Tianjin explosions: The big questions that still remain

Tianjin, China (CNN)When the wind blows in this Chinese port city, shards of glass still rain down from damaged buildings.

But many here are now more worried about a potential threat they can’t see: pollution from the hazardous materials that ignited, sending a towering cloud of fire and smoke shooting into the sky.

“We are concerned that certain chemicals will continue to pose a risk to the residents of Tianjin,” the environmental group Greenpeace said. City residents shared similar fears on social media.Despite reassurances from authorities, what might linger in the air or water is one of several big questions that remain unanswered in the aftermath of the Wednesday night disaster that erupted from a chemical storage warehouse.

The explosions, one of which was the equivalent of more than 20 tons of TNT, are already confirmed to have taken the lives of 50 people and injured more than 700. Many others remain unaccounted for.What chemicals did the warehouse store?
Tianjin officials say they are unable to give a detailed list of exactly what chemicals were being stored at the warehouse.

Gao Huaiyou, the deputy director of the city’s Work Safety Administration, said Friday the warehouse was only a temporary storage facility. Materials were kept there briefly when they arrived at the port and before they were transported elsewhere.

The warehouse site has been destroyed by the explosions, he told a news conference, and managers of the facility have provided “insufficient information” about what was stored there.

Sodium cyanide, a highly toxic chemical that can rapidly kill humans exposed to it, was one of the materials , Gao said.

Greenpeace, citing a local monitoring station, said it believed other dangerous chemicals stored at the site included toluene diisocyanate and calcium carbide.

Gao said further investigation, including checks of customs records, would be needed to try to establish the types and amounts of the chemicals at the warehouse.

What is the environmental toll?
Wen Wurui, Tianjin’s environment protection chief, said Thursday that some chemical levels in the area were higher than normal but that they wouldn’t be dangerous to human health unless someone is exposed to them for long periods.

The wind has so far been helping by blowing fumes out to sea rather than toward the center of the city, said Feng Yinchang, a professor at Nankai University who spoke at the official news conference Friday.

The state-run news agency Xinhua issued a warning telling people not to spread rumors about the situation, including the air quality in Tianjin and Beijing, which is about 110 kilometers (70 miles) away. Some social media posts about the disaster were deleted from platforms in China.

Officials say they have blocked off sewage pipelines that run from the port industrial area where the warehouse was located into the sea in an effort to prevent polluted water flowing out.

But Greenpeace warned that the possibility of rain Friday could pose more challenges by setting off reactions and washing chemicals into the ground. Toluene diisocyanate and calcium carbide both react violently with water, it said.